Hydrostatic transmissions for track-type tractors commonly have each of a pair of substantially identical control linkage assemblies connected to the individual servo valves for selectively rotating the valve spools of the servo valves for operation of the transmission. Each of the control assemblies normally have several links and levers. Heretofore, with such control linkage designs, the individual levers and links have been connected to the respective valve spools in a piecemeal fashion after the pumps and servo valves have been installed in the transmission case. One of the problems encountered therewith is that all adjustments to the control linkage to center the valve spools must be made after all the components are assembled. Likewise, the adjustment to synchronize one control linkage with the other also has to be made after all the components are connected to the servo valves within the transmission case. Furthermore, repair or servicing of the servo valves requires that many of the levers and links be removed individually for access to the servo valves and when they are reassembled, the adjustments to center the valve spools and synchronize their movement must be made again. Also, since the servo valves are not directly interconnected one with the other, once the control linkages are connected to the servo valves and the adjustments made to center the valve spools, slight distortions in the transmission case can throw the adjustments off.